Chronic pain is a major source of human suffering and a major economic problem in American society. Because the problem has long gone unrecognized, there has been little research on which to base improvements in pain patient management. This application requests support to continue our multidisciplinary research program on chronic pain. We propose to carry out seven interrelated research projects involving varying disciplines that will shed light on the mechanisms of pain, the development of pain chronicity, the clinical manifestations of chronic pain, and the treatment of chronic pain. These consist of two studies to be done on the Clinical Pain Service, an additional study of chronic pain patients, and four laboratory investigations. Two of these will employ animal physiology, the third is an animal pharmacology project, and the fourth will investigate chronic pain patients in a human subjects laboratory. In order to accomplish this we will establish a multidisciplinary network of scientific interchange, collaboration, and resource sharing that enhances and expedites the work done under each of the individual projects. Interchange among project leaders will be both formal and informal including monthly project seminars and semi-annual consultation visits by outside scientists.